where \(P_i^{\rm {source}} \gtrless 0\)  depending on whether the machine is
a generator or a motor. \(P_i^{\rm diss}\)  and \(P_i^{\rm acc}\)  are the
dissipated and accumulated power, respectively. The power flow between
two units \(i\)  and \(j\)  is given by [1]}, [2]}
\(P_{ij}^{\rm flow} = -P_{ij}^{\rm MAX} \sin (\theta _j - \theta _i),\) 
